During the opening decades of the 19th century, Central and South America turned to revolution. The idea of liberty had stirred the people of Latin America from the time the English colonies gained their freedom. Napoleon's conquest of Spain and Portugal in 1808 provided the signal for Latin Americans to rise in revolt. By 1822, ably led by Simón Bolívar, Francisco Miranda, José de San Martín and Miguel de Hidalgo, most of Hispanic America – from Argentina and Chile in the south to Mexico in the north – had won independence.

The people of the United States took a deep interest in what seemed a repetition of their own experience in breaking away from European rule. The Latin American independence movements confirmed their own belief in self-government. In 1822 President James Monroe, under powerful public pressure, received authority to recognize the new countries of Latin America and soon exchanged ministers with them.  He thereby confirmed their status as genuinely independent countries, entirely separated from their former European connections.

At just this point, Russia, Prussia, and Austria formed an association called the Holy Alliance to protect themselves against revolution. By intervening in countries where popular movements threatened monarchies, the alliance – joined by post-Napoleonic France – hoped to prevent the spread of revolution. This policy was the antithesis of the American principle of self-determination.

As long as the Holy Alliance confined its activities to the Old World, it aroused no anxiety in the United States. But when the alliance announced its intention of restoring to Spain its former colonies, Americans became very concerned. Britain, to which Latin American trade had become of great importance, resolved to block any such action. London urged joint Anglo‑American guarantees to Latin America, but Secretary of State John Quincy Adams convinced Monroe to act unilaterally: "It would be more candid, as well as more dignified, to avow our principles explicitly to Russia and France, than to come in as a cock‑boat in the wake of the British man-of-war."

In December 1823, with the knowledge that the British navy would defend Latin America from the Holy Alliance and France, President Monroe took the occasion of his annual message to Congress to pronounce what would become known as the Monroe Doctrine – the refusal to tolerate any further extension of European domination in the Americas:

The American continents ... are henceforth not to be considered as subjects for future colonization by any European powers

We should consider any attempt on their part to extend their [political] system to any portion of this hemisphere, as dangerous to our peace and safety.

With the existing colonies or dependencies of any European power we have not    interfered, and shall not interfere. But with the governments who have declared their independence, and maintained it, and whose independence we have ... acknowledged, we could not view any interposition for the purpose of oppressing them, or controlling, in any other manner, their destiny, by any European power in any other light than as the manifestation of an unfriendly disposition towards the United States.

The Monroe Doctrine expressed a spirit of solidarity with the newly independent republics of Latin America. These nations in turn recognized their political affinity with the United States by basing their new constitutions, in many instances, on the North American model.